The process of reducing steel by rolling is a well developed art in the manufacture of steel products. The above mentioned U.S. Patent is capable of providing a method of mounting a roll on a driving capstan in a swift and efficient manner such that the roll and capstan rotate concentrically. The apparatus described above will function perfectly well within certain torque and roll diameter limitations.
As designers of steel mills call for increased capacity, the demand for a method of mounting a large reduction roll on a large capstan in such a manner as to transmit a large driving torque to the roll is a trend which will not be deterred.
Not only must the rotating capstan transmit torque to the reduction roll during a rolling operation with no slippage, but the roll must be capable of being mounted on the capstan in a swift and efficient manner in such a way that the roll mounted on the capstan rotates concentrically with the capstan. Also when the surface of a roll has deteriorated to the point where it must be refurbished, the roll must be capable of being quickly demounted from the capstan drive in preparation for replacement with a new or refurbished roll. This particular method of mounting a roll on the driving capstan lends itself to preserving the surface integrity of the two mating surfaces i.e. the roll and the capstan. Because the surface of the capstan is in its normal unexpanded state during the roll demounting and mounting operations, there is substantial clearance between the mating surfaces of the roll and capstan, hence little or no surface abrasion occurs during these operations.
The above U.S. Patent is perfectly capable of providing such a method of quickly demounting a used roll and remounting a new or refurbished roll on a capstan such that the capstan and the newly mounted roll rotate in a concentric relationship. It is only when certain torque and roll diameters are exceeded beyond certain prescribed limits that an alternate method of mounting and demounting must be found.
The success enjoyed by U.S. Pat. No. 5,700,233 is generally thought to have been achieved by the use of a wedge plug which is threaded into the internal cavity in the hub of a rotating capstan such that once a roll is mounted on the hub, the threaded plug is moved axially within the hub to expand the entire circumference of the hub on which the roll is mounted.
There are distinct advantages to this method of mounting a reduction roll:
1) rolls are easily mounted on the driving capstans while the capstan is in its unexpanded state,
2) when the capstan is expanded the entire circumference of the capstan is expanded uniformly under the mounted roll to provide a stable concentric mounting arrangement for the roller on the driving capstan.
3) The level of skill required to remove and replace a reducing roll with another roll which is concentrically mounted on the capstan shaft is not as great as with prior art mounting techniques.
4) Because of the simplicity of method of mounting the reducing roll on the capstan, and the reduction of components in the driving interface between the capstan and the roller, it is possible to speed up the change over time for roll replacement and thus increase the rolling capacity of the mill.
5) Wear of the mating surfaces of the roll and capstan is minimized during the life time of the capstan, because of the method of mounting the roll on the capstan and the shape of the surfaces. which eliminates roll slip on the capstan.
This invention provides a novel method of mounting and demounting rolls on a capstan drive which is ideally suited to rolls of a prescribed size wherein large driving torques and substantial reduction forces are imparted to the rolls by the driving capstans. The method of mounting the roll on the capstan of this invention includes the presence of a suitable spline drive system in the interface between the roll and the capstan.
The spline drive provides for a positive placement of the roll on the capstan mating face and the spline interface assures a positive drive with no slippage. After mounting a roll on the splined capstan the surface of the capstan mating interface is expanded, preferably by the use of a wedging plug similar to the one shown in FIG. 5 of the aforementioned patent.
Ideally it will be found that this invention will produce the best results if the projecting splines on the roll are about half the width of the upstanding intermeshing splines on the capstan. This configuration assures the easy interchange of rolls on the unexpanded interface of the capstan drive while allowing sufficient area of expansion of the capstan interface (by the wedge plug) to preserve concentricity during a rolling operation.
The presence of any infinitesimal wear which may occur on the surface of the capstan or rolls over a lifetime of the capstan in a steel mill is easily offset by the expandable surface of the capstan.